The present disclosure relates to a light emitting device and a light emitting module.
In recent years, light emitting devices employing light emitting diodes (LEDs) have been widely used in a variety of applications, and LEDs have many advantages including low power consumption, long life, and high reliability. In view of this large and expanding range of uses, light emitting devices require emission properties that are appropriate for a given application. For example, a light-emitting element (e.g., an LED) that emits ultraviolet rays may be used as a light source for hardening ink in an inkjet recorder, as described by Japanese Patent Application No. 2009-51095 A. This inkjet recorder includes a holder that ejects ink from an ink head onto a medium to be printed while moving in a main scanning direction, and a lamp that radiates light to harden the ink ejected from the ink head while moving in the main scanning direction together with the holder.
In the inkjet recorder disclosed in JP 2009-51095 A, an ultraviolet light source is provided that includes a plurality of LEDs arranged in lines as the lamp. However, since the ink head and the ultraviolet light source are positioned relatively close to each other in the inkjet recorder, the light emitted from the light source reflects from the medium or the like and then radiates in the ink head direction and may accidentally harden the ink.
To reduce light radiated in the ink head direction, or in the lateral direction (also known as “stray light”), some inkjet recorders are proposed to devise their entire structures or modify the light-source structure. This may complicate the entire structure of the inkjet recorder or the light-source structure therein, and this may also result in insufficient suppression of the stray light.
These problems are not unique to the inkjet recorder, and other uses of light emitting devices often require appropriate light distribution characteristics in order to reduce the light emitted in unnecessary directions.